With the development of modern industrial techniques, no single year has passed recently without seeing newly developed automobile engines and other various types of engines having increasingly larger precision designs. Today, it is our common knowledge that irrespective of their compact designs modern engines can develop large powers. Most of these engines, however, are so designed as to develop an output by actuating their pistons or rotors with pressure developed from an explosive combustion of an air/fuel mixture. The operation of these engines, therefore, inevitably accompanies a development of exhaust gas which causes air pollution and other various public nuisances. Besides, these engines mostly employ petroleum as their fuel, the limited resources of which is one of the greatest problems that is now being faced by the present world. In view of these circumstances, it is most desired by various industrial fields to develop a low cost engine which can take the place of conventional gasoline engines.